Photoelectric cell



Feb. 25, 1947. w o 2,416,604 PHOTOELEC'IRIC CELL Filed Dec. 8; 1945 SE'LENIUH Inventor Henry T Wrobel, b WW 5) I 1 His Attorney Patented Feb. 25,1947

PATENT orrlcr.

2,418,604 rno'ronnnc'raic can.

Henry T. Wrobel, Lynn, Mesa, asaignor to General Electric Company, a corporation of New York Application December 8, 1945, Serial No. 633,836 4 Claims- (GL Mil- 63) The present invention is an improvement in photoelectric cells; and it is the object of myinvention to provide a hermetically sealed structure which will be rugged and compact, and completely protected against environmental infilldeleterious vapors or gases.

In accordance with my present invention, I have provided strong, compact, hermetically enclosed photoelectric devices of structural simplicity. In such devices a metal plate forming the base of a photoelectric cell constitutes part of the sealing enclosure. This metal base plate is provided with a perforation containing a sealed-in plug of vitreous material through which passes one of the conductors leading to the photoelectric element. A sealed photoelectric device embodying my invention is described in the following specification and is shown in the accompanying drawing.

a hermetically sealed cell embodying my invention; Fig. 2 is a top View; and Fig. 3 is a perspective view showing the base construction.

In the construction of the cell, the base plate 25 l, which may consist of iron, nickel, or other suitable metal, is provided.wlth a thin layer 2 (Fig. 3) of photosensitive material, as, for example, a coating of selenium, by a method described in Hewlett Patent 2,298,670. The base plate is provided with an opening 3, as shown in the drawing. After appropriate heat treatment (described in this patent) whereby the selenium layer 2 is converted into a light-sensitive state, thin films 4, 5 consisting respectively of cadmium and platinum are successively superimposed on the selenium layer. These metal layers l, 5 which are thin enough to be capable of transmitting light to the photosensitive material serve as a A contact ring 6 40 current-conveying electrode. of cadmium (shown of somewhat exaggerated thickness in Fig. 3) is superimposed on the layer 5 by any suitable method, for example by spray deposition, or by a Schoop gun. A thin layer of lacquer (not shown) is applied over the platinum film 5. The lacquer layer improves the output of the cell. I

In a plug I of glass is embedded a sealed-in metal conductor 8. The glass is hermetically joined to the rim of a tubular extension 9 of the base plate. For example, theglass may be fusionsealed to a u-shaped annular sealing eyelet "I.

The inner flangeoi the eyelet ll is joined to the glass plug 1 and the outer flange is joined by 10 ture.

of the base plate I. The fusion-sealed glass and 5 conductor 8 and the contact ring 6. ences, such as the entry of moisture, fungus, and

In the assembly of the component parts it is necessary to keep the temperature of the selenium film below approximately 100 C., except for a short time application of an elevated tempera- This result can be attained by carrying heataway from the cell elements during heating steps by conduction to an adjacent cooler mass of metal or the like. Rapid localized heating can be effected also by inductive electric heating. For example, a flanged ring I2 is joined at its lower edge t9 the support I by soldering, the solder metal filling the outer peripheral channel on the base plate I. Flow of heat from the fused solder to the selenium is reduced by an inner 9 h nn 1 ll 'rn 1 In the drawing, Fig. 1 is a vertical section of c a e 6 upper mwardy bent flange of the ring I! is sealed to a glass cover plate It.

" The glass and the metal flange are chosen to have substantially the same coeflicients of thermal expansion.

The tubular extension 9 is externally screwthreaded and providedwith binding nuts H, as shown on the drawing, to permit attaching the photoelectric device to a support or electric terminal which is indicated at Ill. Contact may be made by screwing the threaded extension into a threaded member (not shown). An electrical connection between a conductor (not shown) and the terminal of the conductor 8 can be made by the binding nuts IS;

The space within the sealed envelope constituted by the described members may be evacu ated'through an opening at (Fig. 1). The opening 20 may be suitably sealed'after evacuation. The space within the photoelectric device after evacuation may be filled with a suitable gas, or mixture of gases. A plug 2| sealing the opening has been conventionally indicated.

, What I claim as new and desire to secure by' Letters Patent of the United States is:

no contact with said photosensitive surface, a closure of sealing material for the opening in said base plate, a cover of radiation-transmitting material mounted above said photosensitive surface, means for sealing the edge of said cover to said base soldering or welding to the tubular extension 8 lo plate, an electrical conductor passing through said sealing material and electrically joined to said contact-making means.

2. A sealed photoelectric cell comprising a metal base plate having an opening extending therethrough, a layer of selenium on said plate, a light-transmitting metal coating superimposed on the selenium, a closure comprising a sealing plug of insulating material externally closing the opening in said base plate, a conductor embedded in said sealing plug, a radiation-transmitting window mounted over said selenium-covered base plate, means for hermetically sealing the edge of said window to said base plate, and means for electrically connecting said embedded conductor an said light-transmitting coating, and external electric terminals for said base plate and said embedded conductor.

3. A. hermetically sealed photoelectric cell comprising a metal base plate having a perforation extending therethrough, a layer of selenium 20 applied to the surface of said plate, a light-transmitting, metallic coating superimposed over said selenium layer, a metallic flange joined to the edge of said base plate. and extending above said layer of selenium, a cover of transparent material fusion-sealed to the edge of said flange and enclosing said coated selenium layer, a plug of. vitreous material fusion-sealed in said perforation and a conductor hermetically sealed in said plug and extending therethrough into electrical contact with the metallic coating on said selenium layer.

4. A hermetically sealed photoelectric cell comprising a metal base plate having an opening extending therethrough; a layer of selenium on said, plate, peripheral channels adjacent to one another and to the edge of'said plate, mean for, making electrical contact with said selenium layer, a plug of vitreous material sealing the opening in said base plate, a conductor sealed into'said plug and joined to the contacting means for said selenium, a window of radiation-transmitting material mounted above the selenium layer and sealed in the outermost peripheral channel, and external electric contacts for said base plate and said sealed-in conductor for the selenium layer.

HENRY '17. wRoBEL, 

